"Not even to do a tour but just to be in the public eye the way Justin is, everything you do as an artist is put under the magnifying glass. All eyes are on you and the smallest mistake becomes your world," he told BBC News.

Ne-Yo, 30, asked critics to take that into consideration before lashing out at the 19-year-old pop prince.

But he admitted stars have to take some responsibility for their own actions too.

"I don't think anybody deserves any pity or anything like that. This is the life you ask for, but people need to take into consideration it's so trying," he explained.

Ne-Yo's remarks come as a representative for Justin said on Friday the singer is still feeling "under the weather".

Justin is still scheduled to perform at the O2 Arena in London again tonight.

The singer earlier took to Twitter to explain his brush with paparazzi.

"Ahhhhh! Rough morning. Trying to feel better for this show tonight but let the paps get the best of me..." he wrote.

"Sometimes when people r shoving cameras in your face all day and yelling the worst thing possible at u...well I'm human. Rough week. Not gonna let them get the best of me again. Gonna get focused on this show tonight. Adrenaline is high now. Gonna put it on the stage. Only way someone can break u is if u let them (sic)."